Tenofovir (TDF and TAF)

Tenofovir is an antiviral drug used to treat HIV and hepatitis B and to prevent HIV (PrEP). Gilead Sciences sells it in two forms. The older form, tenofovir disoproxil fumarate (TDF), is in drugs such as Viread, Truvada, Atripla, Complera, and Stribild. The newer form, tenofovir alafenamide (TAF), received its first FDA approvals in 2015 and is in drugs such as Genvoya and Descovy.

Thousands of patients sued Gilead, mostly in California state court, alleging that TDF caused kidney damage and bone density loss and that Gilead delayed releasing TAF, which they said was gentler on the kidneys and bones. The plaintiffs' main theory was unusual: they did not claim TDF was defective, but that Gilead was negligent in the timing of bringing a safer alternative to market.

On August 3, 2026, the California Supreme Court ruled 6 to 1 for Gilead, holding that drug makers do not owe users of a non-defective drug a duty of care about when to develop and sell a potentially safer alternative. According to Gilead, the ruling directs judgment in its favor on the California state court TDF claims. As of September 2026, that decision ends the main path these cases were using, though anyone with a pending claim should get individual legal advice about what it means for them.

The case shows how mass tort claims can rise or fall on a single legal question decided by a high court. See our guides on class actions versus mass torts and what happens when a case loses.